Dr. John C. Howell Department of Physics and Astronomy University of Rochester
Our group studies entanglement, weak field detection, light-atom transients and slow light. For the creation of entanglement, we use spontaneous parametric down conversion, a nonlinear process by which one photon splits into two photons in a noncentrosymetric crystal. We have studied both discrete and continuous variable (time energy or transverse momentum position) entanglement. For a brief overview of momentum position entanglement from SPDC (here). In collaboration with Bob Boyd's group from the Institute of Optics, we demonstrated that we can obtain a high resolution image of an object in any set of conjugate planes without changing the source, which is not possible classically. We demonstrated a dramatic violation of the momentum-position Einstein Podolsky Rosen paradox using both transverse and longitudinal momentum position entangled photons. We have also used SPDC to achieve discretely entangled polarization entangled photons. Using the discretely entangled photons, we have demonstrated a phase-covariant cloner. We are also working on several quantum measurement theory and entanglement measures.
Using coherent atomic ensembles we study electromagnetically induced transparency transients, slow light and all-optical buffering. One of our major goals is to measure cross-phase modulations at the single photon level. We recently demonstrated that we could impress images onto pulses having less than a single photon and delay these images in hot atomic vapors by many times their pulse length.
Dr. John C. Howell